1. Field of the Invention
The present invention relates to a hearing system comprising a hearing device to which an external audio signal is provided via a wireless, typically a radio frequency (RF) link. The invention also relates to a system for providing audio signals to a hearing device via a wireless link and to a method for monitoring a hearing system comprising a hearing device to which audio signals are provided via a wireless link.
2. Description of Related Art
It is well known to provide an external audio signal to a hearing aid via a radio frequency (RF) link, usually a frequency modulated (FM) link. The RF receiver can be integrated within the hearing aid or it can be an external component which is connected to the hearing aid via a suited and often standardized mechanical and electrical interface. A common application of such systems is the education of students in a classroom by a teacher. In this case the external audio signal is the teacher's voice which is picked-up by a microphone and is sent to the hearing aid of each student via the RF link. Another application of such a wireless system is the case in which parents want to communicate with their child wearing a hearing aid via a wireless microphone and a RF link to the hearing aid.
Conventionally, single channel FM receivers were used for establishing the RF link between the remote audio signal source and the hearing aid. Such systems are available with a “no FM” indicator LED indicating the absence of a carrier on the receiving channel. Such conventional devices are strictly unidirectional, with no signal being sent back from the RF receiver.
More recent devices are designed as multi-channel receivers capable of changing between several audio signal transmission channels, i.e. frequency bands. With such devices, for example, each teacher may use his own transmission channel. Further, the students may be addressed individually via associated transmission channels. The selection of the receiving channel of the RF receiver may be controlled automatically, for example, by a wireless control panel installed at the wall of each classroom.
Further, it is known to use an RF link for remote programming of a hearing aid, respectively an FM receiver. An example of a multichannel RF system for a hearing aid is described in WO 02/23948 A1, wherein the RF receiver connected to the hearing aid also is adapted for remote programming via an FSK (frequency shift keying) modulation used for data transmission between the remote programming unit and the RF receiver. Such FSK link is bidirectional, wherein the RF receiver may transmit information regarding the version of the software installed in the hearing aid to the remote programming unit. It is also mentioned in WO 02/23948 A1 that the bidirectional link for remote programming also could be an inductive link rather than a RF link.
In products which are presently on the market the bidirectional remote programming wireless link may be used for reading identifying information such as serial number, school and student's name from the RF receiver.
An example for a wireless remote control for a hearing aid is given in EP 0681411 B1, wherein the hearing aid has a transmitter/receiver unit for establishing wireless communication with the transmitter/receiver unit of a remote control, wherein audiometric data, hearing parameters, algorithms, fuzzy input and configuration information can be transmitted from the hearing aid to the remote control.
U.S. Pat. No. 5,721,783 describes a “distributed” hearing system, comprising an earpiece including a speaker and a microphone and a body-worn remote processor unit between which a bidirectional RF link is established for transmitting audio signals generated in the earpiece by the microphone to the remote processor unit for signal processing, with the processed audio signals being sent back from the remote processing unit to the earpiece for providing an acoustic signal via the speaker in the earpiece to the user. Thus, the RF link is used for bidirectional transmission of audio signals. A secondary wireless link may be provided to the remote processor unit for supplying external audio signals, such as from a telephone, to the speaker of the earpiece.
There are many applications of a hearing device provided with external audio signals via a wireless link in which it would be desirable to know whether the user of the hearing device properly receives the transmitted external audio signal. This applies particularly to the case in which the user of the hearing device is a child. The reason is that usually adults will easily remark and complain about non-working radio systems, while this cannot be expected in all cases from children, even more so in classroom applications.
Consequently it is an object of the invention to provide for a hearing system comprising a hearing device provided with an external audio signal via a wireless link, which allows a person, such as teachers or parents to monitor the reception of the external audio signal by the user of the hearing device. It is a further object of the invention to provide for a corresponding system for providing audio signals to a hearing device via a wireless link. It is a still further object of the invention to provide for a method for monitoring a hearing system comprising a hearing device provided with external audio signals via a wireless link.